Co2+/Co3+ratio dependence of electromagnetic wave absorption in hierarchical NiCo2O4–CoNiO2hybrids

Amorphous hierarchical NiCo₂O₄–CoNiO₂hybrids have been successfully fabricatedviaa facile one-pot hydrothermal route, followed by morphologic conversion into urchin-like structured NiCo₂O₄–CoNiO₂nanorods and irregular-shaped hierarchical NiCo₂O₄–CoNiO₂polyhedral nanocrystals through air-annealing treatment at 450 °C and 650 °C, respectively.